FREE MATHS GUIDE
Common algebra mistakes and how to check them
A mistake can show exactly which idea needs attention.
Expressions and equations
Simplifying an expression and solving an equation are different tasks. Ask whether there is an equals sign and what the question wants. You cannot “solve” an expression without a relationship.
Brackets and signs
For −2(x − 3), both terms are multiplied by −2, giving −2x + 6. Explain each multiplication before combining terms. Check a numerical substitution in both expressions.
Keeping equations balanced
To solve 3x + 5 = 20, subtract 5 from both sides, then divide by 3. State the same operation on each side instead of relying on a vague rule about moving terms.
A useful checking routine
Substitute an answer into the original equation, not only the rearranged version. Keep an error log with the example, the mistaken step and the reason the correction works.
Try this next
Choose one action from this guide, try it on a fresh piece of work and note what you can do independently. Bring the work and one specific question to your teacher or tutor.
A clearer next step
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